程式設計@筆記

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) { //判斷按下返回鍵
AlertDialog.Builder alert=new AlertDialog.Builder(MainActivity.this); //創建訊息方塊
alert.setTitle("離開");
alert.setMessage("確定要離開?");
alert.setPositiveButton("是", new DialogInterface.OnClickListener() { //按"是",則退出應用程式
public void onClick(DialogInterface dialog, int i) {
MainActivity.this.finish();//關閉activity
}
});

alert.setNegativeButton("否",new DialogInterface.OnClickListener() { //按"否",則不執行任何操作
public void onClick(DialogInterface dialog, int i) {
}
});
alert.show();//顯示訊息視窗

return true;
}
return super.onKeyDown(keyCode, event);
}

}